In typical telematics applications, a telematics unit in an automobile or truck uses one primary communication link between itself and a designated telematics service center to relay voice and data content. Most often voice and data are transmitted over the same communication link, either periodically with separate data and voice sessions over the same communication link, or concurrently with voice and data transmitted at the same time but on different channels.
Voice and data are transmitted using a preferred type of communication link. While digital cellular transmissions are becoming the preferred communication link for many types of communications, there needs to be alternatives when the primary or preferred connection fails or is unavailable. With the advent of digital cellular communications, multiple communication links become inherently available to an in-vehicle communications device. The voice and data communications are transmitted by several different communication link types including analog cellular calls, digital cellular calls, short message service transmissions, and transmissions over a digital Internet protocol (IP) link.
The first information that is conveyed after the establishment of a communication link between a mobile vehicle and telematics service center may be critical with information such as the identification of the telematics unit, location of the mobile vehicle, and event type. For example, when an airbag is deployed, the telematics unit might send out a short message to a call center conveying information on the identification and location of the vehicle with the deployed airbag. If the communication link to the telematics service center fails before essential data is sent, the call center may not be able to take appropriate action and deliver necessary services.
The example just given demonstrates the need for a backup strategy to provide alternative communication links when the first link fails. A method for reestablishing wireless communications would benefit from a strategy that determines the type of communication link failure and evaluates factors that could affect the success of the same or another link type before the voice or data communications are reestablished. The result may be more reliable communications between the mobile vehicle and the telematics service center, particularly during critical events such as times of vehicle inoperability and driver discomfort. The end result would be higher confidence that critical data will be received by the telematics service center, increased subscriber satisfaction, and improvement of telematics services.
Therefore, the intent of this invention is to provide an improved method for reestablishing communication links between a mobile vehicle and telematics service center. The approach would evaluate information on the communication link failure and other condition factors to determine which type of communication link should be attempted next, overcoming the deficiencies and obstacles described above.